The present invention relates to a method of manufacturing a semiconductor device, and more particularly to an effective etching process by using a check pattern provided on a semiconductor substrate.
A plurality of semiconductor elements are manufactured in a semiconductor wafer through various process steps including etching processes. Generally, the etching processes are conducted by using photo-resist of different patterns as masks to form openings in an insulating layer formed on a major surface of a semiconductor substrate, that is, the semiconductor wafer, electrodes, and wiring layers on the insulating layer. The etching processes are classified into isotropic etching and anisotropic etching. A wet etching employing etching liquid is the isotropic etching, and a dry etching in which etching liquid is not used but etching gasses in a chamber is used includes both of the isotropic etching and the anisotropic etching according to the kinds of gasses used and the manner of applying electric field in the chamber. The anisotropic etching can shape a fine pattern of a film precisely because a side etching phenomenon (etching proceeds horizontally under a mask member) does not occur. However, when the anisotropic etching is conducted, a material under the film to be etched must be strictly selected so that the material is not etched during the etching process. Namely, in the anisotropic etching, differences in etching speeds of various materials are sometimes small and therefore, there are many restrictions in etching conditions and in selection of materials of the film to be etched and a substrate or a layer under the film to be etched. On the other hand, in the isotropic etching, differences in etching speeds of various materials are large in many cases. Therefore, the isotropic etching can be easily used in manufacturing the semiconductor device. However, the side etching phenomenon under the mask member is inevitable in the isotropic etching. Therefore, when a fine pattern is to be formed on the film by the isotropic etching, a precise control of the etching and a reliable checking of the etching are necessary.